The subject of the invention is a further development of press machines, principally fast eccentric press machines for increased human safety and reduced pollution of the environment, i.e., the atmosphere.
Fast, mechanically operated eccentric press machines have been used for a long time in the different areas of industry, e.g. mintage, coining, sheet forming, punching, etc. In the use of these machines, as a consequence of the fast operation, great care must be taken to ensure the safety of the person handling the machine.
In the case of the mechanically switched, so-called rotary bolt lock types used earlier, the pressing motion could only be turned off and on at a single point of the machine""s stroke. Therefore if the hand of the operator got into the working rangexe2x80x94in the absence of the possibility of turning the press offxe2x80x94it was unavoidably fractured by the machine. To prevent it, the so called two-hands starter was used, where the operator had to operate simultaneously two separate trip-levers with the two hands to turn on the stroke of the pressing machine. This solution however slowed down considerably the operation of the machine making impossible to utilise its advantage: the fast operation; thus, the number of pieces pressed per hour remained at a very low value. The operating personnelxe2x80x94paid at piece wagexe2x80x94tried to inactivate the two-hand starter, resulting in serious injuries, hand amputations. For this reason the rotary bolt machines were banned in most of the countries, although they were very simply built and operated very reliably.
To replace the banned machines, the more complex and rather more expensive machines with sliding sheet clutch were used, which could be turned off and on at any point of the pressing stroke movement. Should a person""s hand get into the working range, this could for instance be sensed, and the machine stopped with fast breaking by a photocell. Problems rose however with this type of machines too.
One of the problems is that although large, over dimensioned friction clutch was built into the pressing machine, it took 3-5 seconds to arrest the large rotating and jigging mass in motion, and during that time the fast pressing motion could just crush the members or other alien parts that got into the working range.
The other problem is that significant quantities of oil vapour are produced during the operation of the large friction clutch polluting the air of the workshop. Oil vapours of the atmosphere may cause infection of the respiratory tract and cancer of the lung.
The aim of the present study is the further development of the earlier, mechanically activated press through electrification so as to ensure faster stopping and thus safer operation than that of the known solutions, and preventing at the same time the pollution of the plant""s atmosphere with oil vapours.
The invention stemmed from the discovery, that it is not necessary to arrest the rotating and jigging mass of the pressing machine to avoid accidents, as the accident is caused exclusively by the upper and lower parts of the press-head working in the work range. That is in case of danger it is sufficient to separate the two parts of the press-head by a fast electrically switched releasing action, thereby arresting the lower part of the press-head and removing it from the work range. The effective speef of the electric switching action is improved by arranging an electromagnet for releasing engagement between the upper and lower part of the press-head directly on the press-head.
Therefore the aim of the invention is to construct pressing machines, principally fast pressing machines with pressing heads forced into longitudinal jigging and oscillating motion through crank arm by eccentric axle eccentric disk featuring a press-head having a lower pressing block removable from the work range located over the bench, and an upper pressing block capable of sliding relative to the lower pressing block and forced into a jigging motion by the crank, and having alongside an element joining the lower pressing block to the upper one.
The aim set is achieved by a pressing machine, particularly a fast operating pressing machine equipped with a pressing head forced into longitudinal jigging motion in a working range over a bench by an eccenter disk, having an eccentric shaft, through a crank arm, said pressing head having a lower pressing block removable from the work range above the bench and an upper pressing block arranged slideably in relation to the lower pressing block and forced into jigging motion by the crank arm. There is a connecting element releasably connecting said lower pressing block to the upper pressing block; said lower pressing block having at least one of a suspension point and a lifting point; a suspending element is connected to said suspension point, suspending element is cast through reels and strained by a counterweight and a stop impacting onto the upper dead point position of the jigging motion of the upper pressing block. Said lifting point being elevated by a cylindrical spring and a backstop impacting onto the upper dead point position of the jigging motion of the upper pressing block.
The invented pressing machine features a pressing head having an electromagnet for operating said connecting element between a connecting position, wherein the lower pressing block is fastened to the upper pressing block, and a released position, wherein said lower pressing block can freely slide in relation to said upper pressing block. Thereby the connection between the upper and lower pressing block can be broken, thereby motion of the lower pressing block can be stopped while the eccentric disk, its shaft and any flywheel or similar inertial mass connected with the upper pressing block continues to rotate.